Pressure relief device

ABSTRACT

A pressure relief device is provided. The pressure relief device includes a sealing member and a low-pressure support member that is adapted to provide support to the sealing member when the sealing member is subject to a certain pressure differential. The low pressure support member includes an annular flange and at least one supporting projection. A cutting element is adapted to puncture the sealing member when the sealing member is subject to a predetermined pressure differential. The pressure relief device may further include a high pressure support member and safety heads forming a pre-torqued assembly. The supporting projection may optionally include an area of weakness either wholly within or on the periphery thereof.

REFERENCE TO PRIOR APPLICATIONS

This is a continuation of application Ser. No. 10/787,185, filed Feb.27, 2004 now U.S. Pat. No. 7,011,104, which claims the benefit of U.S.Provisional Application No. 60/450,360, filed Feb. 28, 2003, all ofwhich are incorporated herein by reference.

FIELD OF THE INVENTION

This invention generally relates to a safety device for a storage and/orpressurized system. More particularly, the present invention relates toa pressure relief device for a sealed system.

BACKGROUND OF THE INVENTION

Many industries utilize systems that hold or process a pressurizedfluid. Each such system typically includes a safety device designed toprevent the over-pressurization or under-pressurization of the system.In an emergency situation where the pressure differential between thesystem and the atmosphere endangers the physical integrity of thesystem, the safety device will create an opening to provide a vent pathto relieve the pressure differential within the system. The openingallows fluid to flow into or out of the system to reduce the magnitudeof the pressure differential in the system.

Some systems, such as, for example, systems used in the food processingindustry, require protection from both over-pressure situations andunder-pressure situations. In these types of systems, an under-pressuresituation, or vacuum, within the system can damage sensitive equipment.In the food & drug processing industries, for example, a vacuum may becreated in a system when the system is being cleaned after a completionof a process. Typically, these types of systems are cleaned and/orsterilized with a steam spray apparatus that removes any product orcontamination from the system after a processing operation is completedand before the next processing step or cycle begins. If the system isnot properly controlled during steam cleaning, a sudden vacuum can bedeveloped, which may cause damage to the system. For example, if coldwater were introduced to the system while steam cleaning, the steam maycondense and create a vacuum situation.

Thus, to completely protect such a system, the pressure release devicemust provide two-directional pressure relief. The first direction ofpressure relief prevents damage or safety hazards resulting from anover-pressurization, or a positive pressure differential situation. Thesecond direction of pressure relief prevents damage or safety hazardsresulting from under-pressurization, or a negative pressure differentialsituation. Since pressurized systems and atmospheric storage systems aretypically designed to withstand a greater positive pressure differentialthan a negative pressure differential, an appropriate two-directionalpressure relief device should have the ability to function when exposedto significantly different pressure differentials.

It should be noted that some systems are unlikely to encounter anover-pressure situation and, thus, the only risk is exposure to anegative pressure differential. In these types of systems, a pressurerelief device need only protect the system from a negative pressuredifferential.

Some systems require pressure protection at very low levels, measured in“inches of water column” rather than “pounds per square inch.” This typeof low pressure protection may be required in both over-pressure andunder-pressure directions, or just in one direction.

A typical two direction pressure relief device includes a sealing memberthat is sealingly engaged with the system. The sealing member issurrounded by a pair of support members. One support member releases theseal when the seal is exposed to a predetermined positive pressuredifferential and the other sealing member releases the seal when theseal is exposed to a predetermined negative pressure differential. Toprovide protection from a negative pressure differential only, thepositive pressure support member may be omitted.

The positive pressure support member provides a backdrop for the sealingmember and is configured to withstand a predetermined force. As thepositive pressure in the system rises, the seal moves against thepositive pressure support. When the pressure reaches a predeterminedlevel, the positive pressure support releases the seal to create a ventpath and reduce the pressure in the system. Typically, the positivepressure support member is a generally solid unit that has a series ofholes, slits, or perforations. The holes allow fluid to enter the systemif the seal releases under a negative pressure differential and theslits allow the support member to open when the positive pressuredifferential reaches a predetermined level. However, when opening in thenegative pressure differential direction or in low pressure singledirection applications, the positive pressure support does not alwaysfully open, which results in an obstructed flow path for the ventingfluid.

The negative pressure support, often referred to as a “girdle,” istypically disposed between the system and the seal. When a lightnegative pressure differential acts on the seal, the seal moves towardsthe system and into contact with the girdle. The girdle buckles when theseal experiences a negative pressure differential. The amount of girdlebuckling is directly related to the magnitude of the experiencedpressure differential. The same girdle and seal combination may be usedto provide a single direction low pressure relief device for eitherpositive or vacuum relief.

However, the force of the negative pressure differential on the seal andgirdle arrangement may not physically open the seal. Thus, a knife blademay be positioned adjacent the girdle to puncture the seal when thegirdle buckles sufficiently under the negative pressure differential. Ifthe girdle buckles progressively, as opposed to instantaneously, theknife blade may gently tear the seal providing a very small pressurerelief path.

The flow path created through the seal may depend upon the size of theopening in the seal and the configuration of the positive pressuresupport. The larger the opening in the seal, the greater the flow paththrough the pressure relief device. However, the positive pressuresupport does not open when the seal opens under a negative pressuredifferential and thus acts as an impediment to fluid flow. The positivepressure support may include openings, or perforations, that allow fluidto flow through the seal under these conditions. The positive pressuresupport may limit the size of the created flow path to about 50% of thenominal cross sectional area of the pressure relief device.

In light of the foregoing, there is a need for a pressure relief devicethat (1) provides a high flow area for both positive and negativepressure releases; (2) consistently opens at a predetermined pressuredifferential in both the positive and negative directions; (3) providesa two-way device that operates at low pressures in both directions or atwidely different set pressures in each direction; and provides reliableand improved opening in a low pressure direction.

SUMMARY OF THE INVENTION

In one aspect, the present invention is directed to a pressure reliefdevice. The pressure relief device includes a sealing member and alow-pressure support member that is adapted to provide support to thesealing member when the sealing member is subject to a certain pressuredifferential. The low pressure support member includes an annular flangeand at least one supporting projection. A cutting element is adapted topuncture the sealing member when the sealing member is subject to apredetermined pressure differential. The pressure relief device mayfurther include a high pressure support member and safety heads forminga pre-torqued assembly. The supporting projection may optionally includean area of weakness either wholly within or on the periphery thereof.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory onlyand are not restrictive of the invention, as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of this specification, illustrate one embodiment of the inventionand together with the description, serve to explain the principles ofthe invention.

FIG. 1 is a side cross-sectional view of a pressure relief deviceaccording to an exemplary embodiment of the present invention;

FIG. 2 is a top view of a low-pressure support member and a cuttingelement according to an exemplary embodiment of the present invention

FIGS. 3 a-3 j are top views of a low-pressure support member inaccordance with several exemplary embodiments of the present invention;

FIGS. 4 a to 4 j are top views of a cutting element in accordance withseveral exemplary embodiments of the present invention; and

FIG. 5 is a top view of a first support according to an exemplaryembodiment of the present invention.

DESCRIPTION OF THE EMBODIMENTS

Reference will now be made in detail to exemplary embodiments of thepresent invention, examples of which are illustrated in the accompanyingdrawings. Wherever possible, the same reference numbers will be usedthroughout the drawings to refer to the same or like parts. An exemplaryembodiment of a pressure relief device of the present invention is shownin FIG. 1 and is designated generally by reference number 20.

In accordance with the present invention, there is provided a pressurerelief device for a pressurized system. As used herein, the term“pressurized system” includes any system that typically uses a pressurerelief device adapted to open and create a vent path when exposed to apressure differential that is typically measured in inches of watercolumn. These system include, for example, systems designed to operateat pressures above atmospheric pressure and storage systems designed tooperate at or near atmospheric pressure but may become plugged and,thus, require a pressure relief device. The pressure relief deviceincludes a sealing element that is engageable with the system.Preferably, the sealing element is disposed between a pair of safetyheads that are, in turn, sealingly engaged with the system. The presentinvention contemplates, however, that the sealing element may besealingly engaged with the system in any similar manner, such as, forexample, sealed between a pair of pipe flanges in the system.

As illustrated in FIG. 1, pressure relief device 20 includes a seal 22.Preferably, seal 22 includes an outer peripheral edge 21 that issealingly engaged between a first safety head 34 and a second safetyhead 36. Seal 22 may be engaged between safety heads 34 and 36 by aseries of bolts (not shown) configured to connect the safety headstogether. As is well known in the art, safety heads may be pre-torqued.In a pre-torqued safety head design, a pressure relief device such asseal 22 is independently sealingly engaged between safety heads 34 and36 prior to final installation of the device for applications in thefield of use. This prior engagement saves time and minimizes thelikelihood of damage to the pressure relief device during the finalstage installation within the pressurized system. The pre-torqued designalso provides the ability to remove the pressure relief device from thepressurized system for service, inspection, and maintenance, while stillmaintaining an independent sealing engagement of the pressure reliefdevice between the companion safety heads 34 and 36

Pressure relief device 20 may be engaged with the system such that firstsafety head 34 is disposed adjacent the system. First safety head 34includes a bore 30 that defines a fluid passageway. When first safetyhead 34 is engaged with the system, bore 30 allows the fluid in thesystem to contact seal 22, thereby exposing seal 22 to the pressurewithin the system.

Seal 22 may be made of a flexible material that responds to the pressuredifferential between the system and the surrounding environment. Forexample, seal 22 may flex in the direction of arrow 48 when the systemis experiencing a negative pressure differential, i.e. the pressure inbore 32 of second safety member 36 is greater than the pressure in bore30 of first safety member 34. Seal 22 may flex in the direction of arrow46 when the system is experiencing a positive pressure differential,i.e. the pressure in bore 30 of first safety member 34 is greater thanthe pressure in bore 32 of second safety member 34. Preferably seal 22is made of a flexible material, such as, for example, TEFLON. It iscontemplated, however, that seal 22 may be made of any type of flexiblematerial, such as plastic or metal.

In accordance with the present invention, the pressure relief device mayprovide pressure relief for the system when the sealing element isexposed to a negative pressure differential and/or a positive pressuredifferential. The pressure relief device may include a low-pressuresupport and/or a high-pressure support. The low-pressure support may beadapted to support the seal when the seal is exposed to a negativepressure differential. The high-pressure support may be adapted tosupport the seal when the seal is exposed to a positive pressuredifferential. If the particular application requires one-way pressurerelief, either the low-pressure support member or the high-pressuresupport member may be omitted, depending upon the pressure differentialmagnitude at which pressure relief is desired.

In accordance with the present invention, the pressure relief deviceincludes a low-pressure support member. The low-pressure support memberis adapted to provide support to the sealing member when the sealingmember is subject to a first pressure differential, such as, for examplea negative pressure differential. The low pressure support memberincludes an annular flange and at least one supporting projection.

As illustrated in FIG. 1, pressure relief device 20 includes alow-pressure support member 24. Low-pressure support member 24 includesan annular flange 25 and at least one supporting projection, which maybe, for example, arched section 23. Flange 25 may be disposed betweenouter peripheral surface 23 of seal 22 and first safety head 34.

As shown in FIG. 2, annular flange 25 defines an opening 27. Archedsection 23 extends across opening 27 from one side of annular flange 25to the opposite side of annular flange 25. As shown in FIG. 1, archedsection 23 projects away from annular flange 25 and first safety head34. When viewed from the side, arched section 23 may form an arch thatextends over the annular flange 25.

In the exemplary embodiment illustrated in FIGS. 1 and 2, arched section23 is offset from a centerline of opening 27. It is contemplated,however, that arched section 23 may be disposed in alignment with thecenterline of opening 27 or at any offset from the centerline of opening27.

Low-pressure support member 24 may also include a transition section 28and a support tongue 29. Referring to FIG. 1, each of the transitionsection 28, support tongue 29, and arched section 23 provide support forseal 22 when seal 22 flexes in the direction of arrow 48, such as inresponse to a negative pressure differential. Seal 22 will drape overthe arched section 23. Due to the offset position of arched section 23,a portion 31 of seal 22 may move further in the direction of arrow 48than the remainder of seal 22. It is contemplated that the configurationof transition section 28 and support tongue 29, as well as the number ofsupport tongues 29 may be varied to achieve the desired support of seal22.

Arched section 23 is adapted to release seal 22 when the pressuredifferential over seal 22 reaches a predetermined magnitude. As thepressure differential acting on seal 22 increases, the resulting forceexerted on arched section 23 will also increase. When the exerted forceexceeds the structural integrity of arched section 23, arched sectionwill buckle to thereby release seal 22.

The force at which arched section 23 will buckle is determined by manydesign parameters. For example, the shape of arched section 23, such asthe thickness and width of arched section 23, will affect the force atwhich arched section 23 will buckle. Various exemplary configurations ofarched section 23 are illustrated in FIGS. 3 a-3 j. One skilled in theart will recognize that the design parameters of arched section 23 maybe varied in any number of ways to control the force and which archedsection buckles.

The type of material used to construct arched section 23 will alsoaffect the force at which arched section 23 will buckle. An archedsection 23 made of a stronger material will buckle at a greater forcethan an arched section 23 made of a weaker material. The material for aparticular arched section 23 may be selected to provide the structuralsupport required for the intended application. It is contemplated thatarched section 23 may be made from any type of material, including, forexample, plastic, metal, or ceramic.

It is contemplated that the force and location at which arched section23 buckles may be further controlled by introducing one or more areas ofweakness 40 to arched section 23. Each area of weakness 40 may reducethe structural integrity of arched section 23 at a certain location inarched section 23. As shown in FIGS. 3 a, 3 b, 3 c, 3 d, and 3 f, areaof weakness 40 may be a notch, a groove, or a hole. Area of weakness 40may also be another type of structural weakness, such as, for example, adimple or a score or other intentionally introduced structural defect.It is also contemplated that arched section 23 may include multipleareas of weakness 40 at any location wholly within or along theperiphery of arched section 23.

In addition, as illustrated in FIG. 3 j, the force and location at whicharched section 23 buckles may be controlled by a combination of factorssuch as both the shape of the arched section, as well as the size andlocation of an area of weakness 40. In the embodiment of FIG. 3 j,opening 27 is equally divided by a centerline and arched section 23 isdisposed within the opening such that a portion of the arched sectionlies on one side of the centerline and the remaining portion of thearched section lies on the opposite side of the centerline of opening27. In the particular embodiment of FIG. 3 j, the roots of the archedsection 23 (i.e. where the arched section connects with the flange) aredisposed on one side of the centerline and the peak of the archedsection 23 is disposed on an opposing side of the centerline.

One skilled in the art will also recognize that the force at whicharched section 23 collapses may be varied by changing the size,location, and number of areas of weakness 40 in arched section 23. Inaddition, the direction and manner in which the arched section collapsescan be controlled depending on the size, location, and number of areasof weakness 40 provided in arched section 23.

In addition, as shown in FIG. 3 h, the area of weakness in archedsection 23 may be a cut 42 that extends across arched section 23. Cut 42may align, for example, with the apex of arched section 23. A connectingmember 43 may connect the two portions of arched section 23. Connectingmember 43 may represent the weakest portion of arched section 23.Accordingly, the force at which arched section 23 buckles may becontrolled by varying any design parameter of connecting member 43.

Introducing one or more areas of weakness 40 to arched section 23 mayprovide consistent buckling characteristics in low-pressure supportmember 24. As the buckling of arched section 23 will likely initiate atarea of weakness 40, the design parameters of an area of weakness 40 maybe controlled to ensure each arched section 23 buckles when exposed to acertain force. Thus, a weakened arch may be used to set a desired burstpressure for a disk. Accordingly, low-pressure support members 24manufactured within the same lot and bearing the same features may beexpected to buckle at or near the same pressure differential or load.

It is further contemplated that the force at which low-pressure supportmember 24 buckles may be altered by including multiple supportingprojections. For example, as shown in FIGS. 3 a and 3 b, low-pressuresupport member 24 may include a second arched section 23′. As shown inFIG. 3 a, second arched section 23′ may mirror first arched section 23.Alternatively, as shown in FIG. 3 b, second arched section 23′ may havea different configuration than first arched section 23. In still anotheralternative, low-pressure support member 24 may include a third archedsection 23″. One skilled in the art will recognize that the force atwhich low-pressure support member 24 buckles to release seal 22 may bevaried by changing the number, size, and location of the supportingprojections. In addition, an area of weakness 40 may be introduced toeach of the multiple arched sections 23 to further control the force atwhich low-pressure support member 24 buckles to release seal 22.Additionally, an area of weakness 40 may be introduced to one or more ofthe multiple arched sections 23 to control which arched section 23 maybuckle first.

It should be noted that a low-pressure support member 24 that has asingle supporting projection or a supporting projection with an area ofweakness may be configured to buckle at a lower force than alow-pressure support 24 with multiple supporting projections.Accordingly, a stronger material may be used in a “single arch”configuration to achieve the same buckling force as a “multiple arch”configuration using a weaker material. This may allow the use of athermally stable material, such as a metal, to construct thelow-pressure support member 24 whereas a non-thermally stable material,such as plastic, was previously required. It is therefore contemplatedthat a low-pressure support 24 in accordance with the present inventionmay endure a greater range of operating temperatures, including, forexample, temperatures above about 170° F.

In accordance with the present invention, a cutting element is provided.The cutting element may be disposed adjacent to the seal. The cuttingelement is configured to open the seal when the seal is released by thelow-pressure support member. The cutting element may include, forexample, a sharpened blade, a pointed instrument, or a combinationthereof.

As illustrated in FIG. 1, cutting element 38 may include a first blade50 that has a point 52. First blade 50 may extend at an angle, α, fromfirst safety head 34. The position and angle, α, of first blade 50 maybe selected to generally align point 52 with arched section 23. Angle αmay, for example, be approximately 5°.

As shown in FIGS. 1 and 2, cutting element 38 may also include a secondblade 56 that has a second point 58 and a third blade 54 that has thirdpoint 60. Each of second and third blades 54 and 56 extend towards point52 of first blade 50. In addition, each of second and third blades 54and 56 may be disposed at an angle, β. Angle β may, for example, bebetween about 0° and 5°.

First, second, and third blades 50, 54, and 56 may be adapted toposition points 52, 58, and 60 in close proximity to each other.Alternatively, first, second, and third blades 50, 54, and 56 may beadapted to space points 52, 58, and 60 a certain distance from eachother. The relative positioning of each point 52, 58, and 60 may bedetermined to optimize the tearing characteristics of cutting element 38for different applications. For example, a different relativepositioning of points 52, 58, and 60 may provide better tearingcharacteristics for differently sized pressure relief devices 20 as wellas for different expected pressure differentials.

As shown in FIG. 2, both arched section 23 and second and third blades54 and 56 may be substantially aligned in a position that is offset fromthe center of opening 27 in low-pressure support member 24. Thispositioning may reduce the impact of cutting element 38 and archedsection 23 on the flow of fluid through pressure relief device 20 whenseal 22 opens. In this manner, the pressure relieving characteristics ofpressure relief device 20 may be optimized.

Cutting element 38 and arched section 23 may be disposed to prevent seal22 from engaging first, second, or third blades 50, 54, and 56 undernormal operating conditions. The general alignment of arched section 23with point 52 of first blade 50 may prevent contact between seal 22 andcutting element 38. In addition, the position of cutting element 38relative to low-pressure support 24 may be adjusted to prevent contactbetween seal 22 and cutting element 38. Also, support tongue 29 oflow-pressure support member 24 (referring to FIG. 1) may be configuredto prevent portion 31 of seal 22 from engaging cutting element 38.

In addition, the configuration of supporting tongue 29 may adapted toprevent seal 22 from engaging first, second, or third blades 50, 54, and56 under normal operating conditions. For example, supporting tongue 29may be aligned with first blade 50. In this position, supporting tongue29 may form a crease or fold in seal 22 under a negative pressuredifferential. This, or other such configurations, may prevent portion 31of seal 22 from engaging cutting element 38.

Cutting element 38 ensures that seal 22 opens optimally whenlow-pressure support member 24 buckles. The buckling of low-pressuresupport member 24 releases seal 22, which will engage points 52, 58, and60 of first, second, and third blades 50, 54, and 56. Points 52, 58, and60 will initiate openings in seal 22. As the seal 22 continues to movein the direction of arrow 48 (referring to FIG. 1), each of first,second, and third blades 50, 54, and 56 will extend the opening in seal22 thereby causing seal 22 to tear along the length of each blade. Thiswill create a substantial opening through pressure relief device 20 thatwill relieve the pressure differential.

Cutting element 38 may be configured to achieve one or more tears in thematerial of seal 22 to thereby increase the flow area through pressurerelief device 20. It is contemplated that many design parameters ofcutting element 38 may be varied to alter the cutting characteristics ofcutting element 38. For example, the shape of the cutting blades and thedesign of the cutting blade edge, i.e. pointed teeth, serrated teeth,scalloped teeth, number and placement of teeth, square cut teeth, etc.,may be varied to alter the cutting characteristics of cutting element38.

As shown in FIGS. 4 a-4 j, cutting element 38 may have any of a varietyof configurations to optimize the cutting characteristics . For example,the angle of each of first, second, and third blades 50, 54, and 56relative to safety heads 34 and 36 may be varied. In addition, each offirst, second, and third blades 50, 54, and 56 may be curved, waved, orbent.

As shown in FIG. 4 b, first blade 50 may extend past second and thirdblades 54 and 56 to a tear-initiating point 62. Tear-initiating point 62may result in an additional tear in the material of seal 22. Theadditional tear may lead to an increased flow area through pressurerelief device 20.

As shown in FIG. 4 c, it is also contemplated that cutting element 38may include an additional blade 50′. As shown in FIG. 4 f, cuttingelement 38 may include an additional set of blades 50′, 54′, and 56′that mirror blades 50, 54, and 56. Alternatively, as shown in FIG. 4 g,cutting element 38 may include a single blade 64 that includes a pair ofbends 66 and culminates in point 52. One skilled in the art willrecognize that various modifications may be made to the cutting elementof the present invention to change the resulting opening in the materialof the seal. Each such variation is considered to be within the scope ofthe present invention. While the cutting blades are illustrated as acomponent of the safety head 34, they may also be configured to beintegral to the rupture disk components 22, 24 and 26 (when required)such that a new blade is provided with each replacement rupture disk,see for example the embodiment of FIG. 4 j.

In accordance with the present invention, the pressure relief device mayinclude a high-pressure support. The high-pressure support member has asubstantially concave surface and a substantially convex surface. Thehigh-pressure support member is adapted to provide support to thesealing member when the sealing member is subject to a positive pressuredifferential. The high-pressure support member is further configured torelease the seal when the seal is exposed to a positive pressuredifferential of a pre-determined magnitude.

As illustrated in FIG. 1, a high-pressure support member 26 may have anannular flange 31, a concave surface 33, and a convex surface 35.Annular flange 31 may be sealed between outer peripheral edge 21 of seal22 and second safety head 36.

As shown in FIG. 5, high-pressure support member includes a main body 68that defines the concave and convex surfaces 33 and 35 (referring toFIG. 1). Main body 68 includes a series of lines 72, which may be, forexample score lines or slits, that divide the main body 68 into petalsections 80. Each line 72 may terminate in a circular opening 74.

High-pressure support member 26 is adapted to prevent seal 22 fromreleasing until the positive pressure or high pressure differential inthe case of a 2-way rupture disk device reaches a predetermined level.When seal 22 is exposed to a positive pressure differential, i.e. thepressure in bore 30 of first safety member 34 is greater than thepressure in bore 32 of second safety member 36, seal 22 will flex intocontact with concave surface 33 of high-pressure support member 26. Thepressure differential will result in a force exerted on high-pressuresupport member 26.

Main body 68 is configured to open along lines 72 when the exerted forcereaches a predetermined magnitude. The force at which main body 68 opensmay be varied by altering one or more design parameters of high-pressuresupport 26. For example, shape and material of main body 68 may bevaried. In addition, the depth, width, and/or length of lines 72 may bealtered. Also, the number and/or location of lines 72 may be varied. Inone exemplary embodiment, a line 72 may extend around the majority ofthe perimeter of main body 68, thereby forming a single petal. It iscontemplated that these variations on the configuration of high-pressuresupport 26, and any other such variations readily apparent to oneskilled in the art, are within the scope of the present invention.

When seal 22 experiences a certain pressure differential that results inthe predetermined magnitude of force being exerted on high-pressuresupport 26, the material of main body 68 will tear along lines 72. Thecontinued force exertion on main body 68 will cause main body 68 tosplit into petal sections 80 thereby creating a central opening throughmain body 68. The force of the pressure differential will also causeseal 22 to tear. In this manner, fluid may be released in the directionof arrow 46.

As also illustrated in FIG. 1, main body 68 includes a series ofopenings 70 that extend through the main body 68. Openings 70 provide aflow path through high-pressure support member 26 when seal 22 ruptureswhen low-pressure support 24 buckles (referring to FIGS. 1 and 2).Openings 70 may be circular as shown. Alternatively, openings 70 mayhave any other shape, such as, for example, hexagonal, square,triangular, or any other shape that provides for a maximum net flow areathrough main body 68 without adversely affecting the structuralintegrity of the high-pressure support member 26.

The pressure relief device of the present invention may be used in asystem that requires one-way or two-way pressure relief. For example, ina system that requires one-way pressure relief in response to arelatively low pressure differential, pressure relief device 20 may beequipped with only low pressure support 24 combined with seal 22. Firstsafety head 34 may be engaged with system 20 for light positive pressurerelief or with system 30 for light vacuum relief.

In addition, the pressure relief device of the present invention may beused to provide pressure relief in a system that is expected toexperience a greater pressure differential in one direction than in theother direction. For example, a system may be designed to withstand agreater positive pressure differential and a lesser negative pressuredifferential. The pressure relief device of the present invention may beoriented with respect to the system to provide the appropriate relief.For example, first safety head 34 may be disposed adjacent the system sothat the low pressure support will release when seal 22 is exposed to apredetermined negative pressure differential. Alternatively, secondsafety head 36 may be disposed adjacent the system so that the highpressure support will release when seal 22 is exposed to a predeterminedpositive pressure differential.

In addition, pressure relief device 20 may be equipped with a sensor(not shown) that provides an indication when the pressure relief deviceopens to relieve a pressure event. For example, as illustrated in FIG.5, high-pressure support 26 may include an opening 76 at the apex ofmain body 68. A sensor may be disposed in opening 76 to provide anindication when seal 22 ruptures. The sensor may be any type of sensorcommonly used to indicate the activation of a pressure relief device.For example, the sensor may be a BURST ALERT® sensor, a broken wiresensor, a proximity switch, a magnetically activated reed switch sensor,a strip type sensor, a magnetically activated reed switch, or anothertype of sensor.

The operation of the aforementioned pressure relief device will now bedescribed with reference to the attached drawings.

In operation, pressure relief device 20 is engaged with a system (notshown). As mentioned previously, the system may be a sealed system thatoperates at pressures slightly above atmospheric pressure or the systemmay be a vented system whose ventilation passage has become plugged.Engagement of pressure relief device 20 with the system exposes seal 22to the pressure of the fluid within the system. Preferably, pressurerelief device 20 forms a fluid tight seal with the system to prevent anyfluid from leaking into or out of the system.

The system is then operated in its normal fashion. If an emergencysituation is encountered and the system experiences an over-pressuresituation, the force of the fluid within the system acts on seal 22 tomove seal 22 against high-pressure support member 26. Main body 68 ofhigh-pressure support member 26 prevents seal 22 from releasing untilthe positive pressure differential reaches a predetermined level.

When the predetermined pressure differential is reached, the force ofthe fluid acting on high-pressure support member 26 through seal 22 willovercome the material strength of high-pressure support member 26. Mainbody 68 will open along lines 72. Openings 74 at the ends of lines 72may act to prevent fragmentation of main body 68. The material of seal22 will also tear under the force created by the pressure differential,thereby creating a vent path for the fluid to escape.

If the system is exposed to a negative pressure differential, theresulting force on seal 22 will act to move seal 22 into engagement withlow-pressure support member 24. Arched member 23 prevents seal 22 fromreleasing until a predetermined pressure differential is experienced.When the predetermined pressure differential is reached, arched member23 buckles at area of weakness 40, thereby releasing seal 22.

Seal 22 moves into contact with cutting element 38. If the material ofseal 22 does not tear initially, contact with point 52 of cuttingelement 38 will puncture seal 22 to initiate a tear. The continued forceof the pressure differential causes seal 22 to tear along first, second,and third blades 50, 54, and 56. If pressure relief device 20 is adaptedfor bi-directional pressure relief, fluid flows through openings 70 inhigh-pressure support member 26 to relieve the vacuum situation.

The introduction of an area of weakness 40 in arched member 23 may leadto an improved opening of seal 22. Area of weakness 40 may cause a rapidbuckling of arched member 23 when the predetermined pressuredifferential is experienced. The rapid buckling may cause seal 22 toengage cutting element 38 at a relatively high velocity and therebygenerate a substantial impact between seal 22 and cutting element 38.This impact may ensure that cutting element 38 punctures and tears seal22 to create a large, unobstructed flow path through pressure reliefdevice 20.

In the pressure relief device of the present invention addition, thepositive pressure support and the negative pressure support areconfigured to support the seal independently of the other. Thus, thenegative pressure differential of the pressure relief device is notdependent upon the positive pressure differential. This allows thepressure relief device of the present invention to be used with anynumber of systems, including those that are designed to handle a highpressure differential in one direction but only able to withstand a lowpressure differential in the other direction.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the assembly of the presentinvention without departing from the scope or spirit of the invention.Other embodiments of the invention will be apparent to those skilled inthe art from consideration of the specification and practice of theinvention disclosed herein. It is intended that the specification andexamples be considered as exemplary only, with a true scope and spiritof the invention being indicated by the following claims.

1. A pressure relief device, comprising: a sealing member having a domedshape including a concave and a convex side; a low-pressure supportmember configured to provide support along the concave side of thesealing member when the sealing member is subject to a certain pressuredifferential, the low pressure support member including an annularflange and at least one supporting projection; a cutting elementconfigured to puncture the sealing member when the sealing member issubject to a predetermined first pressure differential that causescollapse of the low pressure support member; and wherein at least one ofthe cutting element or the at least one supporting projection isarranged to exhibit radial asymmetry.
 2. The pressure relief device ofclaim 1, further comprising: an inlet safety head member positioned onan inlet side of the low pressure support member; an outlet safety headmember positioned on an outlet side of the sealing member; and whereinthe inlet and outlet safety head members sealingly engage the lowpressure support member and the sealing member therebetween.
 3. Thepressure relief device of claim 1, further comprising: a high-pressuresupport member configured to selectively provide support to the sealingmember and wherein the high-pressure support member is configured torupture when the sealing member and high-pressure support member aresubject to a predetermined second pressure differential.
 4. The pressurerelief device of claim 3, wherein the magnitude of the predeterminedsecond pressure differential is greater than the magnitude of thepredetermined first pressure differential.
 5. The pressure relief deviceof claim 3, wherein the high-pressure support member includes a mainbody having a substantially concave surface and a substantially convexsurface, the main body of high-pressure support member having at leastone passageway therethrough and being configured to provide support tothe convex side of the sealing member when the sealing member is subjectto a certain pressure differential.
 6. The pressure relief device ofclaim 5, further including at least one score or slit line formed in anddividing the main body into distinct sections.
 7. The pressure reliefdevice of claim 6, wherein the at least one score line includes a seriesof score or slit lines formed in the main body and dividing the mainbody into multiple petal sections.
 8. The pressure relief device ofclaim 7, wherein the main body is configured to open along the at leastone score or slit line dividing the main body of high-pressure supportmember when a predetermined force, caused by the predetermined secondpressure differential, is exerted upon the sealing member such that thesealing member contacts the concave surface of the main body.
 9. Thepressure relief device of claim 2, wherein the inlet and outlet safetyhead members form a pre-torqued assembly.
 10. The pressure relief deviceof claim 1, wherein the at least one supporting projection of thelow-pressure support member is an arch extending from a first interiorpoint along the annular flange to a second interior point along theannular flange.
 11. The pressure relief device of claim 1, furtherincluding a transition section in the low pressure support memberextending inwardly from the annular flange and configured to providesupport to the sealing member.
 12. The pressure relief device of claim1, including at least one support tongue formed along an interiorportion of the annular flange of the low pressure support member andconfigured to provide support to the sealing member.
 13. The pressurerelief device of claim 10, wherein the annular flange includes anopening having a centerline and wherein the arch is entirely disposed onone side of the centerline.
 14. The pressure relief device of claim 10,wherein the arch is configured to collapse when a predetermined force,caused by the predetermined first pressure differential, is exerted uponthe sealing member such that the sealing member contacts the arch. 15.The pressure relief device of claim 10, wherein the arch includes atleast one area of weakness.
 16. The pressure relief device of claim 15,wherein the at least one area of weakness is formed wholly within thearch.
 17. The pressure relief device of claim 15, wherein the at leastone area of weakness is formed at a periphery of the arch.
 18. Thepressure relief device of claim 15, wherein the at least one area ofweakness comprises a cut that extends across a segment of the arch and aconnecting member connecting the arch across the cut.
 19. The pressurerelief device of claim 10, wherein the low-pressure support memberincludes multiple arches with at least two arches having differentconfigurations.
 20. The pressure relief device of claim 19, wherein oneor more arches include at least one area of weakness.
 21. The pressurerelief device of claim 1, wherein the cutting element includes a bladeand wherein the blade is configured not to contact the at least onesupporting projection as the at least one supporting projectioncollapses.
 22. The pressure relief device of claim 21, where the bladeextends at an upward angle with respect to a plane including the annularflange.
 23. The pressure relief device of claim 22, wherein the cuttingelement includes a second blade and a third blade, the second and thirdblades extending toward the interior of the annular flange.